Antioxidant and antibacterial properties of guava leaf extracts as affected by solvents used for prior dechlorophyllization

The impacts of different solvents used for removing chlorophyll in guava leaf powder on antioxidant and antibacterial properties of resulting ethanolic extracts were studied. Among all solvents, acetone was the most effective in chlorophyll removal, followed by chloroform as indicated by the lowest chlorophyll a and b contents in resulting extract. However, the ethanolic extract from leaf powder dechlorophyllized using acetone (ACE) showed the lowest antioxidant activities, except for H2O2 scavenging activities (744.12 mu mol TE/g), which exhibited the highest value (p<0.05). Extract from chloroform dechlorophyllized leaf powder (CHL) had the highest antioxidant activities (240.78, 2327.42, and 2598.41 mu mol TE/g for DPPH, ABTS, and FRAP assays, respectively), compared to other extracts. For antibacterial activity, ACE had the highest MIC (2.5mg/mL) and MBC (5mg/mL) against all tested microorganisms (p<0.05). Chloroform was the appropriate solvent for dechlorophyllization, and the resulting extract had higher antioxidant and antibacterial properties than others. Practical applications Oxidative processes and microbial spoilage are responsible for deterioration and safety of perishable food. Phenolic compounds extracted from plant materials are gaining more attention because of their remarkable antioxidant and antibacterial properties. Plant extracts can serve as a natural additive that can replace synthetic chemical additives in foods. However, the application of ethanolic plant extract in food is limited because of their characteristic green color. Dechlorophyllization of leaf extract before extraction could be a means for eliminating this limitation. To the best of our knowledge, this is the first report on the effect of solvents used in dechlorophyllization of leaf powder on the antioxidant and antibacterial properties of their resulting extract. The provided information would serve as background knowledge for preparing the plant extracts without discoloration problem. As a consequence, wider use of leaf extracts can be achieved.